Error-correcting typewriter



Sept. 7, 1965 w. H. woLowrrz ERROR-CORRECTING TYPEWRITER Filed July 22,1965 United States Patent 3,204,745 ERRGR-CORRECTING TYPEWRITER WilliamHoward Wolowitz, 1742 Holly St. NW., Washington 12, D.C.

Filed July 22, 1963, Ser. No. 296,754 3 laims. (Cl. 197-91) Thisinvention provides improvements in typewriters, by which they may bespecially adapted for use with ribbons having two or morelongitudinally-extending stripes or sections, one section being inkedfor impressing characters on a paper sheet, and another section beingprovided with a'layer of correction or camouflage material adapted tocover up or conceal any erroneous impressions which may have been made.

Such multiple-use ribbons can be installed in a conventional typewriterand the selection as between (a) the marking or typewriting section ofthe ribbon, and (b) the camouflaging or obliterating section, may bemade by the typist by manipulating the ribbon-field control lever in thesame manner as is used to select between (for example) black and redimprints when a conventional bichrome ribbon was employed. With theerror-correcting ribbon, however, the field-control lever selects as between a black, blue or other color inked section (for typ ing) and anopaque pressure-transferrable white pigment layer for covering uperroneous characters typed on a white paper or other impression sheet.

The normal sequence of operations in using a conventional typewriterwith such an error-correcting ribbon is as follows. The typist, uponmaking an erroneous char acter selection, transposition or the like,backspaces the carriage to bring it to the position where the firsterror was made, then shifts the field-control lever to bring thecorrection strips of the composite ribbon into play, and strikes the keycorresponding to the erroneous. character or characters. This causes thedeposition, precisely over the errors, of a deposit of the (usuallywhite) camouflage material from the correction section of the ribbon;thus causing the erroneous imprints to disappear.

The typist then again backspaces the carriage the necessary number ofsteps, shifts the field-control lever to bring its inking section intoplay, and types the correct character or characters to deposit thecorrect ink imprints as desired. The nature of the (usually white)pigment applied over the erroneous characters is such as to accept theover-inked correct characters neatly.

It is found that the use of such composite error-correcting ribbons isgreatly facilitated if the typewriter is equipped with two separatebackspacing keys, one of these serving for backspacing the carriage forpurposes other than error correction, and the other both backspacing thecarriage and also automatically shifting the ribbon fieldcontrolmechanism to bring the correction stripe into use. The last-named oradded backspace key will then be used by the typist solely forbackspacing to make error corrections, and will eliminate one of theusual ribbon-field changing operations.

Since, after the error or errors has been obliterated by use of thecorrection stripe, correct imprints will thereafter usually be made, ithas been additionally found that the second set of backspacingoperations can be caused automatically to restore the ribbon-fieldselecting lever, or control, back into its normal printing or typingcondition. Thus, the facility with which the typewriter can be employedin connection with an error-correcting ribbon is greatly augmented ifthe typewriter is provided with two separate and distinctively markedbackspacing keys, as follows:

N0. J.-The regular or conventional backspace key, which moves thecarriage in the backward direction a letter-space step at a time, andalso according to the in- 324,745 Patented Sept. 7, 1965 ice ventionthrows the ribbon field-control mechanism into printing position, and

N0. Z.The added or special backspace key which also moves the carriagein the backward direction a letterspace at a time, and throws the ribbonfield-control mechanism into obliterating or correcting position.

The ribbon-field selector is detented in the usual way, so that itremains in the position which was last selected, even if either of thebackspace keys is given several successive impulses, and until eitherthe other backspace key is employed or until the field selector lever ismanually moved to a different position (such as the non-printing orstencil-cutting position).

Typewriters equipped with two separate backspace keys, as abovedescribed, are perfectly satisfactory when employed witherror-correcting composite ribbons. Sometimes, however, the typistwishes to use a black-and-red or other bichrome ribbon or even to putthe field selector in non-print or stencil position. Any use of eitherof the backspace keys might then operate to change the imprint colorfrom that which was originally selected by the typist, in anuncontrolled or undesired manner, or cause an imprint which was notdesired, as in stencil cutting. The present invention therefore providesa design and construction for a typewriter to facilitate its use witherrorcorrection composite ribbons, but in which the automaticribbon-field selecting action may be selectively disabled or dispensedwith when it is not desired. With such a construction, the typewriteritself is completely serviceable for use with either compositeerror-correcting ribbons, bichrome ribbons, or any other ribbons thatthe user may wish to employ.

Briefly, then the invention satisfies the foregoing objects by providinga typewriter (otherwise of any known or conventional construction) withtwo separate backspace keys which respectively operate also to shift theribbon-field selecting mechanism between its respective field-selectingpositions, together with means readily operable by the typist forselectively disabling this fieldselecting operation or restoring it touse.

The invention will be disclosed herein in connection with certainreferred embodiments shown in the drawings, and in which:

FIG; 1 is a fragmentary diagrammatic perspective view of one form of theinvention applied to a known form of typewriter,

FIG. 2 is an enlarged exploded perspective view of a portion of FIG. 1,

FIG. 3 is a view in perspective showing certain of the parts of FIG. 2when the automatic ribbon-field selecting feature is disconnected.

FIG. 4 is a front elevation of a modified form of the invention.

In FIG. 1, those parts of a conventional office typewriter which are notimportant for an understanding of the invention have been omitted, andare to be understood as conventional. The usual roller platen 10 isprovided, to feed and support the impression paper 12, and the usualribbon vibrator 14 is connected to an operator 15 that is common to allof the impression keys such as 13 and 17 so as to lift the ribbon 16into impression position as the type faces approach the platen andpaper.

As is usual in typewriters designed for use with bichrome (for example,red and black) ribbons, the distance the ribbon vibrator is raised ateach keystroke, is determined by the setting of a ribbon-field selectorsuch a a lever 18. For example, with lever 18 in. the position B shownin FIG. 1 the ribbon vibrator 14 will (on each keystroke) be raised thedistance needed to bring the black section of a ribbon into printingposition. If lever 18 is moved to the position indicated by R, keystrokes will cause the vibrator to rise to a higher osition to bring thered ribbon section or stripe into play. the ribbon vibrator will not belifted at all, leaving the ribbon out of use, as when a duplicatingstencil is to be cut.

There are many conventional ways of effecting such contnol of the ribbonvibrator, the one shown in FIGS. 1 to 3 being characteristic of the(Alpina) portable typewriter. In such .a machine, lever 18 i pivoted asat 20 on the typewriter frame so as to project through a slot in thecover 22. The tail of lever 18 is connected by a link 24 to a detent cam26 secured on a control shaft 28. A detent roller arm 30, also pivotedon the machine frame (at 32) has a free roller 34 cooperating with threenotches or indent-s in cam 26 to hold it (and shaft 28) in the positionselected by lever 18. The arm 30 is urged toward the cam by a spring 36connected to the machine frame through a bracket 38 which also supportsthe bearing for shaft 28.

As its lower end, control shaft 28 has an arm 40 linked to lever 42 thatis so connected to the mechanism 44 for lifting and lowering the ribbonvibrator 14, as to select the ribbon field (black or red) or to leavethe vibrator stationary in its lower (stencil) position. The actualdrive for the vibrator is conventional, and therefore is not shown indetail.

Platen roller is mounted on the usual traveling car- Iiage (not shown)to which is secured the rack bar 45 which is driven stepwise (left toright) by a backspacing pawl 46 each time the usual backspace key 48 isdepressed. In the typewriter illustrated in FIGS. 1-3, the key 48operates through its keylever 50 (pivoted at 51) to rock, by means of apin 53 on lever 50, an arm 52 secured to a transverse shaft 54 pivotedin the frame. At its opposite end, shaft 54 has an arm 56 linked to abell crank58 in turn linked to the backspace pawl 46 to step bar 45 (andthe carriage) as described.

To accomplish the aims of the present invention, a-secthe rack -ond(auxiliary) backspace key 62 is provided at the opward as at 28' and hasloosely mounted on it a control disc 66 which is arranged to be rotatedthrough a small angle, left or right, by the respective backspace keys48 and 62. As shown, the keylever 50 is connected by a flexible cord orcable 68 (passing over a pulley 70) to the lower edge of disc 66, and asimilar tube 72 passes over a pulley 74 and is likewise connected todisc66. When either backspace key is depressed, disc 66 will be swung in thecorresponding direction unless it was already in that position. That is,the first operation of either backspace key, following an operation ofthe other one, will shift the disc 66 and leave it in its new positionuntil the other backspace key is again operated.

'As stated, the disc 66 is loose on control shaft 28. To cause theribbon field selection to be changed when the backspace keys areoperated in alternation, disc 66 must rotate shaft 28 through a smallangle, approximating the angle required to shift from black to redprinting with the conventional bichronie ribbon. Also, the connection ofdisc 66 to shaft 28 must be disengage'able by the typist at will, sothat when acorrection ribbon is no employed, the machine will not shiftfrom black to red in an unintended manner; nor will an unintendedimprint be made after backspacing during stencil cutting.

To accomplish this, the forward end 28' of shaft 28 has secured theretoa hub 76 which pivotally carries, as on a cross pin 78 in the hub, apair of U-shaped bails orstaples 80, 82, the formerof which also fixedlymounts a clutch pin 84 engageable in a hole 85 in disc 66 when the bailIn the position marked S, I

bail 80, any depression of the auxiliary backspace key 62 will pullcable 72, and shift disc 66 counterclockwise (if it was not already inthat position). Disc 66, through pin 84, bail 80, hub 76 and controlshaft 28, will cause the ribbon field for correction to be brought intoplay.

If, thereafter, the normal backspace key 48 is operated one or moretimes, the first operation will pull cable 72 and shift disc 66clockwise, similarly causing control shaft 28 to return to the positionin which the ribbon vibrator will bring the printing stripe of theribbon 16 into use. Since the shaft 28 is connected to field selectionlever 18 by cam 26 and link 24, these operations of backspacing with thetwo backspace keys will cause the lever 18 to shift back and forthbetween the positions ordinarily corresponding to black and redprinting.

To permit the typewriter, including the above feature, to be used withordinary black-and-red (bichrome) ribbons, and other non-correctingribbons, as well as for stencil or other non-printing operations ratherthan the special correction ribbon 16, the automatic shifting actionmust be made disengageable. The two bails 80, 82 permit thisdisconnection, as shown in FIG. 3.

The two bails are connected by a tension spring 86, the pointsofconnection (for example, at pins 88, 90) being so located that thespring passes on opposite sides of the axis of pivoting of the bails;that is, the axis of cross pin 78 in hub 76. With the bails 80, 82 inthe FIG. 2 position, pin 84 engages in the hole 85 in disc 66, clutchingdisc 66 to shaft 28, and spring 86 holds ball 80 in that position. Todisconnect the action, the typist lifts bail 80 away from disc 66, andspring 86 snaps across-center (over-center) to bring the bails 80, 82 tothe FIG. 3 position, withdrawing pin 84 from hole 85 and disconnectingdisc 66 from control shaft 28. In either condition, the over-centerspring 86 keeps the bails in their desired positions, and when theautomatic feature is disabled, either backspace key 48 or 62 will beoperable to backspace the carriage in the usual way, without alteringthe ribbon field.

An equivalent arrangement can easily be applied to different makes andmodels of conventional typewriters. For

example, if the normal backspace keylever and the added or auxiliarybackspace keylever are adjacent one another, for example at the rightside vof the keyboard, the arrangement of FIG. 4 may conveniently beemployed.

In FIGURE 4, numerals 92 and 94 designate the shanks of two backspacekeylevers analogous to the keylevers 64 and 50 of FIG. 1, being shown insection as they project forward in front of the usual front wall of atypewriter into the key bank area. The ribbon-field selecting shaft isagain designated 28, since it may be the same in construction andfunction as shaft28 of FIG. 1. Secured to shaft 28 is an operating plate96 which when rocked back and forth about the axis of shaft 28 willcause the selection of .one or the other of the ribbon fields, again bycontrolling .the vertical motion of the ribbon vibrator as above de-.scribed.

On opposite sides of its pivotal axis, the plate 96 has respectivesubstantially vertical slots 98 andv 100, into which slots pass thelower ends of two stiff control'wires vor rods 102 and 104, the ends ofthe rods being bent to retain them in connection with the plate, subjectto the vertical play permitted by the slots. At their upper ends,

these control rods are bent to pass through respective 116 in the frame.

At the point where the interposers pivot on pin 110, they are slotted topermit a limited amount of endwise motion, the slots being indicated atnumeral 118. Springs 112 and 114 are positioned so that they not onlytend to raise the interposers, but they also urge them both to the left,the extent of leftward motion being set by a selector cam 120 alsopointed as at 121 on the machine frame, and having an operating handle122. The limits of motion of this cam 120 are established by stop pins124, 126 in the machine frame. These end positions of the cam are suchas to move the interposers in a generally horizontal path, to bringtheir terminal projections 128, 130 either beneath the respective keylevers 92 and 94, for operation thereby, or to positions slightly to theleft of the planes of such key levers, so that depression of thebackspace keys will not operate the interposers.

The operation will be clear from the above, but will be brieflydescribed, bearing in mind that the position of plate 96 as shown inFIG. 4 indicates that the last backspace key to have been depressed wasthe one connected to key lever 94, since plate 96 is tipped to theclockwise direction. After operation of that backspace key, its keylever 94 was restored upwards by the usual keylever spring, allowinginterposer 106 to rise, but the plate 96 remained tipped clockwisebecause of the presence of slot 98. In this condition, for example, theribbon field selector, controlled by shaft 28, may be in the printing orinking condition, and would remain in that condition until manuallyshifted, or until operation of the other backspace key. In the lattercase, keylever 92 will be depressed, lowering interposer 108, and itscontrol rod or wire 104, being at the bottom of slot 100, will tip theplate 96 into the oppo site (counter-clockwise) condition, and will thusshift the field selecting saft 28 to bring the correction field of theribbon into play.

When it is desired to use the typewriter, so equipped, with an ordinaryblack-and-red, or even monochrome ribbon, or to cut stencils orotherwise perform non-print operations, the handle 122 has only to beshifted to the left, into the dotted-line position, which will allowboth interposers to slide slightly to the left, where their projections128 and 130 will not be engaged by the keylevers 92 and 94.

While the invention has been disclosed herein in connection with certainpreferred embodiments thereof, it will be obvious to those skilled inthe art that it may equally well be accomplished by other and differentmechanisms, and all such variations are intended to be included herein,to the extent that they fall within the scope of the appended claims.

I claim:

1. A typewriter for use with ribbons providing a printing field and aprint-obliterating field, said typewriter including character-printingmechanism, a paper support mechanism, printing control keys, spacingmeans for stepwise moving said mechanisms relative to one another in aforward direction to accomplish printing of a line of characters, aribbon vibrator actuated by the printing control keys to bring a ribbonfield momentarily into operative position upon actuation of each of saidprinting control keys, ribbon field-selecting means for controlling theextent of motion of the vibrator to select the particulat ribbon fieldthat is thus brought into operative position, backspace drive means forstepwise moving said mechanisms relative to one another in the backwarddirection in letter-width increments, a pair of backspace keys bothconnected to operate said backspace drive means, connections betweensaid backspace keys and said field-selecting means to shift the latterbetween position respectively corresponding to that backspace key whichwas last operated, and means for selectively disengaging saidconnections, to permit the use of said backspace keys without alteringthe ribbon-field selection.

2. A typewriter having a reciprocable paper carriage, typing keys, aribbon vibrator actuated by the typing keys to bring a ribbonmomentarily into marking position upon actuation of each of the typingkeys, ribbon field-selecting means for controlling the extent of motionof the vibrator to select the particular ribbon field that is thusbrought into marking position, backspace drive means for stepping saidcarriage reversely to the writing direction in letter-width increment, apair of individual backspace keys both connected to operate saidbackspace drive means, a connection between said backspace keys and saidfield-selecting means to shift the latter to -a position correspondingto that backspace key which was last operated, and means for selectivelydisengaging said lastnamed connection.

3. A typewriter for use with ribbons providing a printing field and aprint-obliterating field, said typewriter including character-printingmechanism, printing control keys, a paper support mechanism, spacingmeans for stepwise moving said mechanisms relative to one another in aforward direction to accomplish printing of a line of characters, meansactuated by the printing control keys to bring a ribbon fieldmomentarily into operative impression position upon actuation of each ofsaid print ing control keys, ribbon field-selecting means to select theparticular ribbon field that is thus brought into operative impressionposition, backspace drive means for step wise moving said mechanismsrelative to one another in the backward direction in letter-widthincrements, a pair of backspace keys both connected to operate saidbackspace drive means, and a selectively engageable connection betweensaid backspace keys and said field-selecting means, operable, whenengaged, to shift the field-selecting means between postionsrespectively corresponding to that backspace key which was lastoperated.

References Cited by the Examiner UNITED STATES PATENTS 656,658 8/00Phelps 197 91 FOREIGN TPATENTS 528,589 11/40 Great Britain.

ROBERT E. PULFREY, Primaly Examiner.

1. A TYPEWRITER FOR USE WITH RIBBONS PROVIDING A PRINTING FIELD AND A PRINT-OBTAINING FIELD, SAID TYPEWRITER INCLUDING CHARACTER-PRINTING MECHANISM, A PAPER SUPPORT MECHANISM, PRINTING CONTROL KEYS, SPACING MEANS FOR STEPWISE MOVING SAID MECHANISMS RELATIVE TO ONE ANOTHER IN A FORWARD DIRECTION TO ACCOMPLISH PRINTING OF A LINE OF CHARACTERS, A RIBBON VIBRATOR ACTUATED BY THE PRINTING CONTROL KEYS TO BRING A RIBBON FIELD MOMENTARILY INTO OPERATIVE POSITION UPON ACTUATION OF EACH OF SAID PRINTING CONTROL KEYS, RIBBON FIELD-SELECTING MEANS FOR CONTROLLING THE EXTENT OF MOTION OF THE VIBRATOR TO SELECT THE PARTICULAR RIBBON FIELD THAT IS THUS BROUGHT INTO OPERATIVE POSITION, BACKSPACE DRIVE MEANS FOR STEPWISE MOVING SAID MECHANISMS RELATIVE TO ONE ANOTHER IN THE BACKWARD DIRECTION IN LETTER-WIDTH INCREMENTS, A PAIR OF BACKSPACE KEYS BOTH CONNECTED TO OPERATE SAID BACKSPACE DRIVE MEANS, CONNECTIONS BETWEEN SAID BACKSPACE KEYS AND SAID FIELD-SELECTING MEANS TO SHIFT THE LATTER BETWEEN POSITION RESPECTIVELY CORRESPONDING TO THAT BACKSPACE KEY WHICH WAS LAST OPERATED, AND MEANS FOR SELECTIVELY DISENGAGING SAID CONNECTIONS, TO PERMIT THE USE OF SAID BACKSPACE KEYS WITHOUT ALTERING THE RIBBON-FIELD SELECTION. 